Nubbed yarn and process for making same



R. F. SPICER ETAL 3,280,546

NUBBED YARN AND PROCESS FOR MAKING SAME 1 Oct. 25, 1966 2 Sheets-Sheet 1Filed June 12, 1964 Oct. 25, 1966 sp c ETAL 3,280,546

NUBBED YARN AND PROCESS FOR MAKING SAME Filed June 12, 1964 2Sheets-Sheet 2 United States Patent M 3,280,546 NIJBBED YARN AND PROCESSFOR MAKING SAME Ronald F Spicer and Preston F. Marshall, Walpole,

Mass, 'assignors to The Kendall Company, Boston,

Mass, a corporation of Massachusetts Filed June 12, 1964, Ser. No.374,743 6 Claims. (Cl. 57-144) This invention relates to novelty yarn ofthe nub type.

More particularly it relates to a nubbed yarn in which the nubs areformed by an interlocking engagement between a core strand and awrapping strand, so that the nubs cannot be displaced or caused to slidealong the core strand.

In the preparation of textured fabrics for the garment, upholstery,drapery, and similar trades, extensive use is made of novelty yarnswhich, by various manipulations in a twisting process, are caused totake on an alternating thick-and-thin appearance. Such yarns generallyinvolve the manipulation of at least two strands. When one strand iswrapped about another rather tightly for a multiplicity of turns, andthis wrapping is carried on at spaced intervals, a so-called knop yarnis formed. A boucl yarn is formed by looping a wrapping strand looselyaround a core strand, and holding the loops in place by a third orhinder strand. Slub and nub yarns are likewise characterized bydeliberately-induced thick and thin places, slubs generally being of asoft nature and possessing tapered leading and trailing edges.

A nub in a yarn is generally a more abrupt discontinuity than the othertypes, and appears as a mass or ball of fibers or filaments scatteredalong the length of the yarn like popcorn threaded on a string. Due totheir generally similar natures, it is not always possible to draw astrict differentiation between slubs and nubs.

In US. Patent 3,041,812, to one of the present inventors, there isdescribed a method of making a novelty yarn, therein called a slub yarn,by the following steps:

(1) Continuously passing a straight tensioned continuous core strandaxially through a cylindrical body of fluid whirling about a centralaxis.

(2) Continuously overfeeding a wrapping strand into said body of fluid,generally tangentially thereof.

(3) Forming doubled-back loops of said wrapping strand around thecircumference of said core strand in an intermittent thick-and-thinmanner.

(4) Withdrawing the composite yarn from the whirling body of fluid.

Such yarns, though useful for many textile applications, suffer from atleast one drawback. The core strand, about which the wrapping strand isdisposed, is maintained under tension during the wrapping process. Thefinal wrap, or nub, therefore, is disposed about a generally straight,smooth, unconvoluted core strand. In the exigencies of weaving andknitting, where the heddle eyes, reeds, or knitting needles exert africtional dragon the yarn, yarns of this type may show a tendency forthe nubbed wrappings to slip or slide along the smooth core, bunchingtogether and destroying the evenly-spaced nub effect which is generallydesirable in fabrics made from such yarns.

We have found that if the core strand is fed to the body of fluid notunder tension but under a controlled degree of overfeed or slack, thecore strand, during the wrapping operation, is twisted into a series ofspaced-apart bifilar pedicled loops. The wrapping strand protrudes inits own loop-like configuration from the core strand loops, and theresulting entanglement or engagement between wrapping strand and corestrand is such as to resist substantially any attempt to slide ordisplace the resulting nub along the axis of the composite yarn.

3,28%,545 Patented Oct. 25, 1966 It is therefore an object of thisinvention to provide a nubbed yarn of unique configuration. It is alsoan object of this invention to provide a nubbed yarn comprising at leasttwo strands, both strands having at intervals a looped configuration. Itis a further object of this invention to provide a nubbed yarn whereinthe nubs are securely fixed in non-slipping relationship to a corestrand. Other objects of the invention will appear more fully from thefollowing description thereof.

The invention will be better understood in connection with the drawings,in which:

FIGURE 1 represents a side elevation of a nubbed yarn of this invention.

FIGURES 2 through 6 represent the initial stages in the formation of theyarn of this invention, showing by stages the formation of convolutionsin the core strand while it is being wrapped by the wrapping strand.

FIGURES 7 through 9 represent further stages in the development ofpedicled loops in the core strand, the wrapping strand being omitted forclarity.

FIGURE 10 represents the interengagement of wrapping strand and corestrand at the base of the pedicled loop of the latter, the wrappingstrand engagement with the core strand in the rest of the loop againbeing omitted for clarity.

FIGURE 11 is a representation of a cross section taken along the yarnaxis through one of the nubs of FIG- URE 1.

FIGURE 12 is a cross-sectional side view of a vortex tube suitable forproducing the yarn of this invention.

FIGURE 13 is a cross-sectional end view of the tube of FIGURE 12.

FIGURE 14 represents schematically a preferred embodiment of the processof the invention.

GENERAL NATURE OF THE PROCESS Referring to FIGURE 14, the core strand 10is supplied from a package 21, threaded over star wheels 22 and 24, anddelivered to the vortex chamber 26 wherein it becomes textured asexplained more fully hereinbelow. Simultaneously one or more wrappingstrands, 12, are delivered from a supply package 34, around the feedwheel 32, to the vortex chamber through the wrapping strand inlet 29.The composite nubbed yarn 36 is drawn from the vortex tube, which isequipped with a tangentially-directed air stream through the inlet 28,and passes around star wheels 38 and 40 to guide roll 42 and Winder 44.

ACTION OF THE VORTEX CELL If the apparatus as set forth above isoperated with the core strand under tension, the result is a wrappedyarn as described in US. Patents 3,076,307 and 3,041,812, to one of thepresent inventors. We have found, however, that a novel and desirableresult is brought about if the core strand tension is decreasedsufiioiently to allow this strand to be influenced by the high twistingenergy of the whirling fluid mass contained within the vortex cell. Theprobable sequence of events is shown in FIGURES 2 through 9.

FIGURE 2 represents an initial stage in the development of a typicalyarn of this invention, wherein the wrapping strand 12, being whirledaround the core strand 10, is doubled thereabout in a bifilarconfiguration headed by a loop 13. Due to the slack in the core strandtension, at hump or bend is formed in this strand, as shown at 11. Thecore strand rotates around the tube axis with a cranking motion at thesame time as the highly overfed wrapping strand is wrapped around thecore strand, as shown in FIGURE 3, where the bend in the core strand hasbeen accentuated, leading to the formation of a core strand loop asshown in'F-IGURE 4. The force of the whirling fluid has by this timecreated many bifilar loops of wrapping strand 12 to engage with the loop11 of the core strand, some of these wrappingstrand loops passingthrough other wrapping strand loops as at 15, and some being twistedalong their length, as shown at 17 in FIGURE 4.

The continued twisting and cranking motion imparted to the core strandthen causes the bend or loop 11 to twist into a crunodal loop, as shownin FIGURE 5, said loop continuing to be twisted into a pedicled bifilarloop as shown in FIGURE 6. The open portion of this loop is filled withbifilar wrapped loops of wrapping stran disposed about the core strand.

When operations are carried out in a chamber about Mr inch in diameterand at an air pressure of 100 p.s.i.g., the characteristic loop formedin the core strand goes through the stages shown in FIGURES 7 and 8,developing numerous strand crossings along its pedicled stem. As thecore strand loop is twisted more tightly, it tendst-o collapse into atight ball as shown in FIGURE 9. In FIGURES 7, 8, and 9, the Wrappingstrand has been omitted for clarity.

FIGURE 10 represents a typical action of the loops of wrapping strand atthe base of the twisted loop of core strand, where the protruding loopsof the Wrapping strand 12 are Whipped around the base of the core strandloop in an interlocking interengagement. To some extent a similar effectis found also in the body of the nub: that is, as the yarn composite ofFIGURE 4, for example, progresses to the tightly-twisted coreconfiguration of FIGURE 9, the longer loops 15, and 17 of FIGURE 4 notonly weave in and out of the twists that are developed in the corestrand, but they are wrapped around the collapsing and tighting corestrand loop configuration.

NATURE OF THE NUBBED YARN The nature of the final product of thisinvention is shown in FIGURE '1, wherein the core strand 10 is gatheredinto a tightly twisted l-oop configuration (reflecting the stage shownin FIGURE 9), with the Wrapping strand 12 disposed in regular wrappingconfiguration between nubs, but within the nub being falsely wrappedaround the core strand in loose doubled loops, and blossoming out into avoluminous burst of yarn expanded into three dimensions. In the nubstructure, the multiplicity of radially-extending loops of wrappingstrand tend to more or less completely obscure the knot-like convolutionof the core strand shown in FIGURE 9, said convolution of the corestrand generally being composed of a shorter length of strand than thelength of wrapping strand present in the nub, and also generally beingmore tightly twisted.

In producing nubbed yarns of this type, a vortex cell of the typedescribed in US. Patent 3,082,591, of March 26, 1963, may be used. Moreconsistently uniform results are realized, however, if the modificationshown in the present FIGURES 12 and 13 is employed. In FIG- URE 12, themain body of the cell 50 is formed from a section of quartz or glasstubing, conveniently inch long with /2 inch outside diameter and 0.273inch inside diameter. The open ends of the tube 50 are partially filledby a piece of glass tubing 62 defining the core strand inlet 52, ,set ina rubber gasket '56, and on the outlet end by a piece of ceramic, brass,or glass tubing 60, defining the nubbed yarn outlet 54, and set in arubber gasket58. A convenient size for the entry tube 62 is 0.152 inchoutside diameter, 0.089 inch inside diameter, and for the exit tube 60,0.187 inch outside diameter and 0.147 inch inside diameter. Thesedimensions are illustrative, not restrictive, and may be varied, cellsup to several inches in diameter having been constructed in accordancewith this invention to operate on coarse cords or ultra-heavy strands.

The air inlet opening and the wrapping strand inlet opening are shown asdotted-lines 28 and 29 at FIGURES distances to which the inlet tube 62and the exit tube 60 project into thecentral chamber of the vortex tube,and are adjustable, as set forth below.

A wide variety of nubbed yarn products can be made, Within the scope ofthis invention, by manipulating the variables in the process. Among thevariables which have been found to influence the thickness or size andthe spacingof the nubs along the composite strand are l the following:

(1) The overall rate of production of the composite yarn.

(2) The rate of overfeed of the core strand.

(3) The rate of overfeed of the wrapping strand.

(4) The total denier and denier per filament of the core strand and thewrapping strand.

(5) The air pressure.

(6) The vortex tube dimensions and settings.

By proper choice of variables, composite nubbed yarns can be made inwhich the size of the nubs varies from about ,5 inch to A inch or more,size being measured by the diameter of the nub in an uncompressed state.The spacing between nubs can be varied from an average of about /2 inchto an average of about 2 inches or more, the exact spacing beingrandomized around these averages. These general figures all relate to asmall vortex cell-- that is, a cylindrical chamber of about 4 inchdiameter and inch high. Large cells give nubs which are coarser anddifferently spaced, depending on the air pressure and on themoduli ofthe strands employed.

The following examples will illustrate various embodiments of theprocess and product of the invention. In Examples 14, the followingfactors were held constant:

(1) The core strand was denier 68 filament nylon with /2 turn ofZ-twist.

(2) The wrapping strand feed rate was 2,534 feet per minute.

(3) The air pressure was 90 pounds per square inch.

(4) The vortex tube dimensions were those set forth above asrepresentative, with the inlet tube 62 projecting inch into the chamber(distance A of FIGURE 12) and the outlet tube 60 projecting inch intothe chamber (distance B of FIGURE 12).

Example 1 Wrapping strand: 55 denier 15 filament dull acetate, with 2turns of Z-twist.

Wrapping strand overfeed: 1250% Composite yarn take-up speed: 187 feetper minute.

Core strand feed rate: 306 feet per minute.

Core strand overfeed: 63%

Calculated denier of product: 972

Measured denier: 970

Size of nubs: about A inch in diameter.

Nub spacing: Ma inch to 1% inches apart.

Example 2 Example 3 Wrapping strand: denier 40 filament. dull acetatewith 2 turns of Z-twist. Wrapping strand overfeed:.-19307 Composite yarntake-up speed: 125 feet per minute.

Core strand feet rate: 485 feet per minute.

Core strand overfeed: 288% Calculated denier of product: 3588 Measureddenier: 3123 5 Size of nubs: about A inch in diameter.

Nub spacing: /2 inch to 1 inch apart.

Example 4 Wrapping strand: 75 denier filament dull acetate with 2 turnsof Z-twist.

Wrapping strand overfeed: 1250% Composite yarn take-up speed: 187 feetper minute.

Core strand feed rate: 548 feet per minute.

Core strand overfeed: 192% Calculated denier of product: 1422 Measureddenier: 1334 Size of nubs: about inch in diameter.

Nub spacing: 1% inches to 2% inches apart.

Comparing Examples 1 and 2, it is seen that increasing the denier of thewrapping strand from 55 to 75, with other factors constant, caused thesize of the nubs to double. In a comparison of Examples 2 and 4, it isseen that the same wrapping strand and wrapping strand overfeed ratewere used. The high rate of core strand overfeed of Example 4, however(192% versus 63% of Example 2), meant that the core strand constitutedover 28% of the calculated denier of the final product, whereas inExample 2 the core strand constituted only 18% of the calculated denierof the final product. It is characteristic of the process of thisinvention that yarns can be produced which are superficially similar,but in which the apparently similar nubs contain varying ratios of corestrand content to wrapping strand content.

It is also characteristic of products made according to this inventionthat although the spacing of the nubs can be varied, as seen from theexamples, the nubs are not precisely spaced equidistant from each otherunder any given set of conditions. The average spacing between ourspaced-apart nubs can be controlled, but individual spacing will varyaround the average. Since nubbed yarns are frequently employed to makefabrics which are highly textured in a randomized fashion, our yarns areeminently suited for such purposes.

The process of this invention is not limited to the use of conventionaltextile yarns in either the core strand or the wrapping strand. Glassstrands, stretch strands (of the multifilament bulked or crimped type)and elastomeric strands such as rubber or spandex may be employed, asillustrated by the following examples. 0

Example 5 Using the same vortex cell and air pressure as in Examples 1through 4, the following all-glass nubbed yarn was made:

Example 6 Again using the same vortex cell and air pressure as inExamples 1 through 4, a stretch-core nubbed yarn was made as follows:

Core strand: denier 17 filament 2 ply, 7 turns of S- twist, Superloftstretch nylon yarn, a product of Leesona Corporation.

Wrapping strand: 75 denier 20 filament dull acetate with 2 turns ofZ-twist.

Wrapping strand overfeed: 1250% Core strand feed rate: 306 feet perminute.

Composite yarn take-up speed: 187 feet per minute.

Core strand overfeed: 63%

Calculated denier of product: 1242 Measured denier: 1180 Nub size: about/8 inch in diameter.

Nub spacing: 1 inch to 1% inches apart.

This yarn is substantially inelastic as produced, and can be handled asany other inelastic yarn through a weaving or knitting process. By usingdry heat, or steaming, or hot water, etc., in finishing the fabric, theabove yarns can be shrunk, with the development of an elasticextensibility. The yarn of Example 6, after steaming, had an elongationof In preparing nubbed yarns of this invention using an elastomeric coresuch as rubber or spandex, the ease of elongation of the core strandpresents certain problems.

First, it is diflicult to measure the rate of overfeed of the input corestrand, due to its elasticity. We prefer, therefore, for any givenelastomeric core strand, to dissect a convenient measured length of thefinal product, say 20 inches, measured without tension. The excess ofcore strand over 20 inches, again measured relaxed, divided by 20, isexpressed as core strand overfeed. This overfeed will generally bebetween 5% and 50%, and the excess elastomeric core strand will be foundin a spaced-apart series of nubs in which the core strand has beentwisted on itself as in FIGURES 8, 9 and 10.

Example 7 With the same conditions as in the previous examples, thefollowing nubbed yarn was made:

Core strand: 280 denier spandex.

Wrapping strand: 75 denier 20 filament dull acetate, with 2 turns ofZ-twist.

Wrapping strand overfeed: 1250% average.

Composite yarn take-up: 224 feet per minute.

Measured denier, relaxed: 950

Nub size: to 05 inch, variable.

Nub spacing: 2 inches to 10 inches apart.

When the acetate wrapping strand was dissolved from a 20-inch length ofrelaxed composite strand by means of acetone, a 24-inch length ofrelaxed core strand was recovered, indicating an average core overfeedrate of 20%.

Although the above examples have illustrated the use only of continuousfilament strands, we have found the invention to apply equally well toregular commercial yarns of spun staple fiber. Such spun yarns may beused as the core strand, as the wrapping strand, or both. Plied yarnsmay be used as either or both core and wrapping strand, as well.

In general we prefer to employ an overfeed of between 15% and 200% onthe core strand, depending on the size and spacing of nubs desired. Whennubs are cut from the composite yarn and untangled, it is found thatfrom /2 inch to 5 inches of core strand, and from 4 inches to 20 inchesof wrapping strand, have been gathered into each nub, within preferredprocessing ranges. It should be appreciated that although the wrappingstrand and core strand are here spoken of independently, the wrappingstrand is actually disposed around the core strand in the form ofdoubled loops while the core strand is simultaneously being formed intoloops, as shown in FIGURES 4 through 10 and as explained above. Thisleads to a unique type of nub formation, characterized by a blossomingeffect and a resistance to slippage of the nubs along the axis of thecomposite yarn.

It has been proposed previously to create nubbed or slubbed yarns byfeeding two yarns into a zone of fluid turbulence, as evidenced by US.Patent 3,118,269 to 7 Bilsky, and U.S. Patents 2,997,837 and 3,043,087to Breen. In addition, fluid turbulence has been used to blow thefilament-s of one strand through the separated filaments of a secondstrand, in a pulsating operation to give a composite yarn in which onestrand is randomly interlaced through the body of another. However, thestructure and properties of such yarns resemble the structure andproperties of the yarns of this invention only superficially.

Having thus described our invention, we claim: 1. A nubbed yarncomprising at least one core strand and at least one wrapping strand,

said wrapping strand being intimately associated with said core strandin the form of doubled-back bifilar loops wound for a multiplicity ofturns around said core strand and possessing no net true twist aboutsaid core strand, the wrapped core strand being at spaced-apartintervals twisted into pedicled loops, the core strand constituting saidpedicled loops being associated, within said pedicled loops, inentangled relationship with said 'bifilar loops of wrapping strand, saidpedicled loops of core strand, together with the wrapping strandassociated therewith within said pedicled loops constituting a series ofnubs spaced along the length of the composite yarn, said nubs beingcharacterized by substantial resistance to displacement along the lengthof said yarn.

2. The product according to claim 1 wherein said 30 core strand is aspun yarn.

3. The product according to claim 1 wherein both said core strand andsaid wrapping strand are spun yarns.

4. The product according to claim 1 wherein the core strand is amultifilament stretch yarn of synthetic polymeric material.

5. The product according to claim 1 wherein the core strand is anelastomeric strand.

6. A process for producing a wrapped nubbed yarn which comprisescontinuously overfeedi'ng a core strand into a vortex cell containing awhirling mass of fluid, in a direction normal to said whirling mass,

continuously overfeeding at least one wrapping strand I References Citedby the Examiner UNITED STATES PATENTS 7/ 1962 Marshall 576 2/1963Marshall 57152 3/1963 Marshall 576 FRANK J. COHEN, Primary Examiner.

J. PETRAKES, Assistant Examiner.

1. A NUBBED YARN COMPRISING AT LEAST ONE CORE STRAND AND AT LEAST ONEWRAPPING STRAND, SAID WRAPPING STRAND BEING INTIMATELY ASSOCIATED WITHSAID CORE STRAND AND POSSESING NO NET TRUE TWIST ABOUT LOOPS WOUND FOR AMULTIPLICITY OF TURN AROUND SAID CORE STRAND AND POSSESSING NO NET TRUETWIST ABOUT SAID CORE STRAND, THE WRAPPED CORE STRAND BEING ATSPACED-APART INTERVALS TWISTED INTO PEDICLED LOOPS, THE CORE STRANDCONSTITUTING SAID PEDICLE LOOPS BEING ASSOCIATED WITHIN SAID PEDICLEDLOOPS , IN ENTANGLED RELATIONSHIP WITH SAID BIFILAR LOOPS OF WRAPPINGSTRAND, SAID PEDICLED LOOPS OF CORE STRAND, TOGETHER WITH THE WRAPPINGSTRAND ASSOCIATED THEREWITH WITHIN SAID PEDICLED LOOPS CONSTITUTING ASERIES OF NUBS SPACED ALONG THE LENGTH OF THE COMPOSITE YARN, SAID NUBSBEING CHARACTERIZED BY SUBSTANTIAL RESISTANCE TO DISPLACEMENT ALONG THELENGTH OF SAID YARN.
 6. A PROCESS FOR PRODUCING A WRAPPED NUBBED YARNWHICH COMPRISES CONTINUOUSLY OVERFEEDING A CORE STRAND INTO A VORTEXCELL CONTAINING A WHIRLING MASS OF FLUID, IN A DIRECTION NORMAL TO SAIDWHIRLING MASS, CONTINUOUSLY OVERFEEDING AT LEAST ONE WRAPPING STRAND TOSAID VORTEX CELL IN A DIRECTION TANGENTIAL TO SAID WHIRLING MASS OFFLUID, CONTINUOUSLY WRAPPING SAID WRAPPING STRAND IN THE FORM OFDOUBLE-BACK LOOPS AROUND SAID CORE STRAND, CONTINUOUSLY TWISTING THETHUS-WRAPPED OVERFED CORE STRAND INTO A SPACED-APART SERIES OF TWISTEDLOOPS, AND CONTINUOUSLY REMOVING SAID WRAPPED NUBBED YARN FROM SAIDCELL.